Metabolic dysfunction-associated steatotic liver disease (MASLD), commonly known as fatty liver disease, is one of the most prevalent chronic liver diseases worldwide and is closely associated with obesity and insulin resistance. A 2026 randomized controlled trial published in Nutrients reported that consuming 200 g of fresh tomatoes and 50 g of tomato paste daily for six weeks was associated with a greater reduction in liver fat, as measured by the controlled attenuation parameter (CAP), compared with a control group. Notably, these changes occurred without significant changes in body weight or body fat, suggesting that tomato consumption may have potential benefits beyond weight management, although further research is needed to confirm these findings. Lycopene, a naturally occurring carotenoid found in tomatoes and other red fruits and vegetables, has also attracted scientific interest for its potential relationship with mental health and neuroprotection. This article explores the findings of the tomato intervention study, summarizes research on lycopene and depressive symptoms and cognitive function, and introduces other natural food pigments, including beta-carotene, lutein, zeaxanthin, anthocyanins, curcumin, and astaxanthin, that have been investigated for their potential health benefits.
Colorful fruits and vegetables provide more than visual appeal to our daily diets. Their distinctive colors often come from naturally occurring bioactive compounds, some of which have attracted considerable scientific interest because of their potential roles in human health. Among these compounds, lycopene, the red pigment found abundantly in tomatoes, has been studied for its antioxidant properties and possible effects on metabolic health.
Recently, research has brought renewed attention to the relationship between tomato consumption and liver health. Other studies have also explored associations between dietary lycopene intake and mental health, as well as its potential neuroprotective effects. Although these findings are promising, it is important to distinguish preliminary evidence from established clinical benefits.
1. A Potential Benefit for Liver Fat
Metabolic dysfunction-associated steatotic liver disease (MASLD), commonly known as fatty liver disease, is one of the most common chronic liver diseases worldwide. It is closely associated with obesity and insulin resistance and may progress to liver fibrosis and even cirrhosis.
In 2026, a randomized controlled trial published in Nutrients reported that a common, affordable, and widely consumed food—tomatoes—may help improve liver steatosis when consumed regularly over six weeks.
The study was conducted by researchers from the Italian National Institute of Gastroenterology and included 79 adults diagnosed with MASLD. Participants were randomly assigned to two groups. Both groups maintained their usual lifestyles throughout the study, with tomato consumption being the only difference between them.
Tomato intervention group (42 participants): Consumed 200 g of fresh tomatoes and 50 g of tomato paste daily.
Control group (37 participants): Avoided all tomatoes and tomato-based products.
The intervention lasted six weeks. At the end of the study, researchers assessed liver fat using FibroScan, a transient elastography technique. The primary measurement was the controlled attenuation parameter (CAP), for which higher values indicate greater fat accumulation in the liver.
The results were notable. The median CAP value decreased by 18 dB/m in the control group, compared with a reduction of 35 dB/m in the tomato intervention group. The reduction in the tomato group was nearly twice that observed in the control group, and the difference between the groups was statistically significant.
After adjustment for potential confounding factors, including age, sex, and body mass index (BMI), the interaction between treatment and time remained statistically significant. This suggests that the observed difference was not readily explained by these measured factors alone.
Even more noteworthy, participants in both groups showed no significant changes in body weight, body fat percentage, waist circumference, or visceral fat during the trial. In other words, the reduction in the CAP value in the tomato group occurred without significant weight loss.
Researchers suggested that the potential benefits may be associated with lycopene, the characteristic bioactive compound in tomatoes, as well as other bioactive substances such as beta-carotene. These compounds have been investigated for their potential roles in regulating liver metabolism. Proposed mechanisms include activating the hepatic SIRT1–AMPK metabolic pathway, inhibiting de novo lipogenesis in the liver, and promoting fatty acid oxidation, thereby potentially reducing lipid accumulation in liver cells. In addition, lycopene may help alleviate oxidative stress and modulate inflammatory signaling, potentially reducing the burden on the liver.
The combination of fresh tomatoes and tomato paste used in the study is also noteworthy. Fresh tomatoes retain vitamin C, which is sensitive to heat, while processing and heating tomatoes can increase the bioavailability of lycopene by breaking down cell walls and making the compound more accessible for absorption. These two forms may therefore provide complementary nutritional benefits.
However, the researchers also emphasized that the study had a relatively small sample size and a short intervention period. It should be considered an exploratory trial, and larger, longer-term studies are needed to validate the findings.
2. Beyond Liver Health: Lycopene and Mental Health
Lycopene has attracted research interest not only for its potential relationship with liver health but also for its possible effects on the brain and mental well-being.
In 2025, researchers investigated the association between dietary lycopene intake and depression among American adults. The study analyzed data from 18,664 participants aged 20 years and older in the US National Health and Nutrition Examination Survey (NHANES) collected between 2007 and 2016. Among the participants, 8.98% had been diagnosed with depression.
The analysis found that participants with depression had significantly lower dietary lycopene intake than those without depression. More than half of the participants with depression (55.07%) had dietary lycopene intake below the median for the entire study population, whereas lycopene intake was distributed more evenly among participants without depression.
These findings suggest an association between dietary lycopene intake and depression status. However, observational data cannot establish that lower lycopene intake causes depression or that increasing lycopene intake can prevent or treat the condition.
In the same year, another study reported evidence of the potential neuroprotective effects of lycopene. In obese mice, daily lycopene administration at a dose of 50 mg/kg significantly improved cognitive function, restored neuronal density in the brain, and increased the levels of key neuroprotective proteins, including brain-derived neurotrophic factor and neuraminidase.
These findings provide further evidence of lycopene's potential biological activity in the brain. Nevertheless, results from animal studies cannot be directly translated into proven benefits in humans, and further clinical research is needed.
3. Lycopene: The “Golden Pigment” of Plants
Lycopene is a member of the carotenoid family and belongs to the tetraterpene group. Its structure consists of eight isoprene units linked through a tail-to-head arrangement. It is a fat-soluble natural pigment found in tomatoes, carrots, watermelons, and other plant foods. The compound was named lycopene because it was first isolated from tomatoes.
Lycopene is an effective natural antioxidant capable of scavenging free radicals. Its antioxidant capacity has been described as approximately 100 times that of vitamin E and more than twice that of beta-carotene, earning it the nickname “golden pigment of plants.”
The human body cannot synthesize lycopene, so it must be obtained through the diet. Lycopene is one of the major carotenoids found in human blood and tissues. It is stored primarily in the liver and adipose tissue, and it can also accumulate in the adrenal glands and prostate.
Lycopene is currently used as a food colorant in a variety of products, including beverages, confectionery, and baked goods. Beyond lycopene, many other natural pigments can contribute both color and nutritional value to foods.
4. Other Natural Food Pigments with Potential Health Benefits
Beta-carotene: Beta-carotene gives carrots, pumpkins, and other orange-yellow fruits and vegetables their characteristic color. It can be converted into vitamin A in the human body as needed, helping maintain normal vision, skin, and mucous membranes.
Lutein and zeaxanthin: Findings from AREDS2, a large randomized controlled trial involving 4,203 participants followed for five years, suggest that supplementation with lutein and zeaxanthin may help reduce the risk of progression to advanced age-related macular degeneration, particularly among individuals with insufficient dietary intake.
Anthocyanins: These pigments give blueberries, mulberries, purple cabbage, and other plant foods their red, purple, and blue hues. A systematic review pooling 49 randomized, placebo-controlled trials found that anthocyanins may improve cognitive performance, including memory, and benefit vascular endothelial function.
Curcumin: A randomized controlled trial involving 367 participants found that turmeric extract improved pain and physical function associated with knee osteoarthritis, with effects comparable to ibuprofen and fewer gastrointestinal adverse effects. Consuming curcumin with black pepper can significantly increase its absorption and bioavailability.
Astaxanthin: This pigment is responsible for the orange-red color of salmon, shrimp, and crabs and is known for its antioxidant properties. A double-blind randomized controlled trial found that daily supplementation with 4 mg of astaxanthin for nine weeks could reduce ultraviolet-induced skin damage.
Taken together, these natural pigments represent an important area of nutritional research. However, their effects vary depending on the compound, dose, formulation, and population studied. Evidence from observational studies, animal experiments, and clinical trials should be interpreted according to the strength and limitations of each study. A balanced diet rich in a variety of fruits and vegetables remains a practical way to obtain these naturally occurring compounds, while no single food or pigment should be considered a substitute for appropriate medical care.
References
[1] Tatoli R, Donghia R, Carella N, et al. Effect of Tomato Consumption on Liver Steatosis in MASLD: A Randomized Controlled Trial (POMOSANO Study). Nutrients. 2026;18(15):2476.
[2] Research on the association between dietary lycopene intake and depression among American adults. Available at: https://mp.weixin.qq.com/s/jf9NTWz7-sy7Vq_Bu8Pbsg
[3] Research on the neuroprotective effects of lycopene and other natural food pigments. Available at: https://mp.weixin.qq.com/s/rNf9j9mgyWnlYjdNV-mKxg